<!DOCTYPE html>
<html>
<body>
<p id="demo">一个段落222</p>
<p id="demo1">一个段落333</p>
<p id="demo2">一个段落444</p>
<p id="demo3">一个段落555</p>
<script>

/* 
function print() {
    document.getElementById("demo").innerHTML = "hhhh"
}
setTimeout(print, 3000)
*/
const fx = (x,y=3)=>{return x*y}    //默认参数
function x1() {return this}

setTimeout(function() {
    document.getElementById("demo1").innerHTML = "hhhh"
}, 3000)
document.getElementById("demo").innerHTML = "aaaa"
document.getElementById("demo2").innerHTML = "3*6="+fx(3,6)
document.getElementById("demo3").innerHTML = x1()
</script>

</body>
</html>